In the process of developing superconducting sensor technology for the next generation of Cosmic Microwave Background (CMB) experiments, we have been working on a design that couples the CMB signal from a microstrip antenna to transition edge sensors (TES). In our detector design, the signal from the microstrip antenna is split into passbands centered at 95 GHz, 150 GHz and 220 GHz [1,2], and is then routed to different transition edge sensors. Making this possible in a compact topology requires crossover structures that isolate the high frequency superconducting lines from each other. Here, we will discuss the design optimization that replaces these superconducting cross-over structures with ground layer embedded cross-under structures. This change reduces the number of required depositions and circumvents liftoff issues associated with cross-over structures. In doing so, we had to ensure no cross talk in the high frequency lines, confirmed by HFSS simulation results. [1] C. M. Posada et al., Supercond. Sci. Technol. 28, 94002 (2015), [2] J. Ding et al., IEEE Trans. Appl. Supercond. 27, 2100204 (2017)